P21C0Cold Start Cylinder 11 Injection Timing
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P21C0 applies only to twelve-cylinder engines (V12 or W12), since passenger-car engines with exactly eleven cylinders do not exist. Examples with direct injection are BMW's N74 twin-turbo V12, found in the BMW 760i and in Rolls-Royce models such as Ghost, Wraith and Dawn, and the 6.3-litre W12 FSI. The code would report that cylinder 11 missed its cold-start injection timing, for instance when the extra injection for catalyst heating is shifted. Whether BMW, Rolls-Royce or Audi use P21C0 is not documented publicly. The legal basis is CARB's demand for separate cold-start diagnostics, allowing the module to tell such faults apart from warm-running timing faults (P021E). Related: P0211 (injector circuit), P0311 (misfire).
- What you may notice
- Check engine light after cold starts
- Barely noticeable on the road; a twelve-cylinder engine masks a single cylinder well
- Likely causes
- LikelyDirect injector of cylinder 11 with changed opening behaviour
- PossibleHeat-damaged wiring or connector at injector 11
- RareInjector driver for cylinder 11 in the engine control module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €250 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.